Piezoelectric motor

Abstract

A piezoelectric motor is disclosed, which comprises a slider including a tabular vibrator in which a standing wave is excited, and a plurality of piezoelectric actuators securely mounted at the parts of the lower surface of the vibrator corresponding to the loop and node of the standing wave and adapted to be deformed in phase with the standing wave.

We claim: 
     
       1. A piezoelectric motor comprising: a first element; a vibrator element mounted adjacent the first element; means for exciting a standing wave in said vibrator element; a plurality of piezoelectric actuators interposed between the vibrator element and the first element; and means providing alternating electrical energy to the piezoelectric actuators for deforming them in a fixed phase relationship with the standing wave thereby to generate a net driving force in one motion direction between the first element and the vibrator element. 
     
     
       2. A piezoelectric motor according to claim 1, wherein the vibrator element is tabular and the piezoelectric actuators are fixed at parts of the vibrator element corresponding to the loop and node of the standing wave. 
     
     
       3. A piezoelectric motor according to claim 2, wherein said means providing causes the piezoelectric actuators fixed on the vibrator element to be subjected to shear vibration. 
     
     
       4. A piezoelectric motor according to claim 2, wherein each of the piezoelectric actuators is a rectangular parallelopiped polarized along respective directions perpendicular to the motion direction; an electrode is mounted on each of two adjacent sides of the rectangular parallelopiped; means connecting the remaining sides thereof that are parallel to the direction of polarization at earth potential; said means providing, impressing a given one of the electrodes on the two adjacent sides with a sinusoidal voltage thereby to select one of the longitudinal motion and the lateral motion of the vibrator element. 
     
     
       5. A piezoelectric motor according to claim 1, wherein the vibrator element is tabular with the adjacent ends of the piezoelectric actuators fixed to the ends of the adjacent surface thereof; the piezoelectric actuators being tabular, elongated along the length of the vibrator element, polarized perpendicular to the length of the vibrator element, and having a central part and ends, with respect to the length, thereof in contact with the first element; and the piezoelectric actuators being polarized in opposite directions on the right and left sides, with respect to the length, of the central part thereof. 
     
     
       6. A piezoelectric motor according to claim 2, including adhesive means for bonding the vibrator element and the piezoelectric actuators and providing electrical insulative and elastic characteristics therebetween. 
     
     
       7. A piezoelectric motor according to claim 1, wherein the vibrator element is annular and made of a piezoelectric material polarized along the radial direction thereof and said piezoelectric actuators are mounted at positions of the maximum amplitude of the standing wave in the vibrator element; and the first element being annular in shape and having means providing contact with the outer periphery of the actuators under spring tension. 
     
     
       8. A piezoelectric motor according to claim 1, wherein a one of the piezoelectric actuators is of rectangular parallelopiped shape having a direction of polarization; said means providing also impressing alternating electric fields in the directions parallel and perpendicular to the direction of polarization respectively thereby to cause a longitudinal vibration and a shearing deformation in phase therewith, thereby generating a driving force. 
     
     
       9. A composite piezoelectric motor according to claim 1, wherein the piezoelectric actuators are four serially connected sectors together forming a single annular member, each sector polarized along the radial direction thereof; said means providing further impressing alternating electric fields in each of said sectors parallel and perpendicular to the direction of polarization respectively thereby to excite a longitudinal vibration and a shear deformation in pbase therewith; means mounting one of said elements for rotating; said one of said elements being an annular slider; and spring means for keeping said one of said elements in contact with the outer periphery of the annular member. 
     
     
       10. A piezoelectric motor comprising: a stator having an upper surface;   a slider;   a slider block movable slidingly on the upper surface of said stator;   a first piezoelectric device connected between said slider block and said slider;   electric means adapted to vibrate said first piezoelectric device in a resonance fashion in a first direction in a plane parallel to the upper surface of said stator;   a second piezoelectric device connected between said slider block and said slider;   electric means adapted to vibrate said second piezoelectric device in a resonance fashion in a second direction different from the first direction in a plane parallel to the upper surface of said stator;   a third piezoelectric device connected between said slider block and said slider; and   electric means adapted to vibrate said third piezoelectric device in a resonance fashion in a direction perpendicular to the upper surface of said stator.   
     
     
       11. A piezoelectric motor comprising: a first element;   a vibrator element constructed of piezoelectric material mounted adjacent the first element;   means for exciting a standing wave in said vibrator element to deform said vibrator with nodes and loops of the standing wave according to the distortion of the piezoelectric material caused by the standing wave, with such distortion being toward and away from said first element;   a plurality of piezoelectric actuators interposed between the vibrator element and the first element respectively a node and loop positions so that the actuators at loop positions will drivingly contact between said first element and said virator and the actuators at node opsitions will have no driving contact between said first element and said vibrator; and   means providing alternating electrical energy to the piezoelectric actuators for deforming them in a fixed phase relationship with the standing wave thereby to generate a net driving force in one motion direction between the first element and the vibrator element.   
     
     
       12. A piezoelectric motor according to claim 11, wherein said means providing causes the piezoelectric actuators fixed on the vibrator element to be subjected to shear vibration. 
     
     
       13. A piezoelectric motor according to claim 11, wherein each of the piezoelectric actuators is a rectangular parallelopiped polarized along respective directions perpendicular to the motion direction; an electrode is mounted on each of two adjacent sides of the rectangular parallelopiped; means connecting the remaining sides thereof that are parallel to the direction of polarization at earth potential; said means providing, impressing a given one of the electrodes on the two adjacent sides with a sinusoidal voltage thereby to select one of the longitudinal motion and the lateral motion of the vibrator element. 
     
     
       14. A piezoelectric motor according to claim 11, wherein the vibrator element is tabular with the adjacent ends of the piezoelectric actuators fixed to the ends of the adjacent surface thereof; the piezoelectric actuators being tabular, elongated along the length of the vibrator element, polarized perpendicular to the length of the vibrator lement, and having a central part and ends, with respect to the length, thereof in contact with the first element; and the piezoelectric actuators being polarized in opposite directions on the right and left sides, with respect to the length, of the central part thereof. 
     
     
       15. A piezoelectric motor according to claim 11, including adhesive means for bonding the vibrator element and the piezoelectric actuators and providing electrical insulative and elastic characteristics therebetween. 
     
     
       16. A piezoelectric motor according to claim 11, wherein the vibrator element is annular and made of a piezoelectric material polarized along the radial direction thereof and said piezoelectric actuators are mounted at positions of the maximum amplitude of the standing wave in the vibrator element; and the first element being annular in shape and having means providing contact with the outer periphery of the actuators under spring tension.